A. Field of the Invention
This invention concerns integrated logic circuits. More particularly, the invention concerns improved Exclusive OR circuit making use of complementary metal oxide semiconductor (CMOS) field effect transistor (FET) technology.
B. Description of the Prior Art
Logic circuits making use of CMOS technology are well known and are currently used in a large number of applications. An Exclusive OR circuit produces a logic zero output when two inputs are brought to the same logic level and produces a logic "1" output when the inputs are brought to different levels. Prior art Exclusive OR circuits in CMOS technology are comprised of 12, or more, devices. A portion of the devices are required to generate the complement signal from the input or true signals. The remaining devices are employed to process the true and complement signals to obtain the Exclusive OR output signal. Exclusive OR circuits having a reduced number of switching elements will permit additional logical functions to be incorporated in a semiconductor chip thereby increasing the logical power of the chip.
An object of the invention is to provide an Exclusive OR integrated circuit fabricated in CMOS technology and having a minimum number of switching elements.
Another object of the invention is an Exclusive OR integrated circuit fabricated in CMOS technology and having a symmetrical topological arrangement.